1. The Field of the Invention
Embodiments of the invention relate to improving fiber optic integrity within an optical component. More particularly, embodiments of the invention relate to optical devices that provide electromagnetic shielding.
2. The Relevant Technology
Fiber optic technology is increasingly employed in the transmission of data over communications networks. Networks employing fiber optic technology are known as optical communications networks, and are typically characterized by high bandwidth and reliable, high-speed data transmission.
To communicate over an optical communications network using fiber optic technology, fiber optic components such as fiber optic transceivers are used to send and receive optical data. Generally, a fiber optic transceiver includes optical subassemblies (“OSA”) such as a transmit optical subassembly (“TOSA”) for sending optical signals, and a receive optical subassembly (“ROSA”) for receiving optical signals.
More particularly, the TOSA receives an electrical data signal and converts the electrical data signal into an optical data signal for transmission onto an optical network. The ROSA receives an optical data signal from the optical network and converts the received optical data signal to an electrical data signal for further use and/or processing. Both the ROSA and the TOSA include specific optical components for performing such functions.
A conventional TOSA includes an optical transmitter such as a light emitting diode (LED) or a laser diode. The optical transmitter generates an optical signal that is launched onto an optical fiber. A plastic barrel is typically used to align and couple the optical signal emission from the optical transmitter with the end of a fiber optic cable for transmission of the optical signal to a fiber optic network. The optical transmitter can be located within a header, such as a TO-Can package, and is typically covered by an at least partially transparent cap (or lid) that protects the optical transmitter and allows the optical transmitter to transmit the optical data signal to an optical fiber. The cap may include a lens for focusing the optical signal transmission.
A conventional ROSA includes an optical receiver, such as a PIN photodiode or avalanche photodiode (“APD”). A plastic barrel is typically used to align and couple the end of a fiber optic cable relative to the optical receiver. This facilitates transmission of the optical signal to the optical receiver. The optical receiver can be covered by a partially transparent cap that protects the optical receiver and allows the optical receiver to receive the optical data signal from the optical cable. The cap may also include a lens for focusing the optical signal transmission.
A typical optical fiber has a core of high refractive index material surrounded by a low-index cladding material. In order for an optical transmitter to transmit an optical signal to an optical fiber, the optical emission of the optical transmitter is aligned with the transmissive core of the optical fiber such that the core of the optical fiber receives a sufficient portion of the emission from the optical transmitter. Likewise, in order for an optical receiver to receive an optical signal from an optical fiber, the active surface of the optical receiver is aligned with the transmissive core of the optical fiber such that a sufficient portion of the optical signal is received by the optical receiver from the optical fiber.
Referring to FIG. 1, a conventional module 100 for coupling an optical device 101 to a fiber optic cable 102 is shown. As shown in FIG. 1, the module 100 has a plastic barrel 103 with an open end 104 that is sized and configured to receive a fiber optic end face 105 of the fiber optic cable 102 in alignment with the optical device 101 mounted on a header 106.
In the case of a ROSA, the optical device 101 includes an optical receiver for receiving an optical signal from the optical fiber 102 and converting the optical signal to an electronic signal. In the case of a TOSA, the optical device 101 includes an optical transmitter for receiving an electronic signal, converting the electronic signal to an optical signal, and transmitting the optical signal to the optical fiber 102. The header 106 has electrical leads 107, sometimes referred to as feed throughs, for providing power and data signals between an OSA printed circuit board (“PCB”) (not shown) and any optical device(s) mounted on the header 106.
A cap 108 covers the optical device 101 mounted on the header 106 for protection of the optical device 101. The cap 106 can be made of an at least partially transparent plastic material, and may include a focusing lens or transmission window for allowing optical signals to travel to or from the optical device 101.
While the header 106 is partially fabricated with metal and provides some electromagnetic shielding, the electro magnetic shielding provided by both the header 106 and the plastic barrel 103 can be insufficient. In some instances, electromagnetic radiation 109A originating from inside the module 100 can be transmitted through the plastic barrel 103 and to the outside of the module. Similarly, electromagnetic radiation 109B may travel from the outside of the module 100 and through the plastic barrel 103 entering into the inside of the barrel causing interference. Such interference can disrupt communication, especially in compact products and products transferring data at high rates where the highest level of attenuation is desirable.
Therefore, what would be advantageous are optical components having additional electromagnetic shielding, thereby reducing, if not eliminating, the adverse effects of electromagnetic radiation on the reception or transmission of optical signals.